sqlite3使用总结

参考文档

官方文档

操做总结

准备工做,引用包，并创建链接

import sqlite3

db_conn = sqlite3.connect('example.db')

建表

db_conn.execute(r'''
CREATE TABLE stocks (
        uuid text, 
        date text, 
        trans text, 
        symbol text, 
        qty real, 
        pricereal
    )
''')

也能够判断表是否存在，若是不存在就新建

db_conn.execute(r'''
CREATE TABLE IF NOT EXISTS stocks (
        uuid text, 
        date text, 
        trans text, 
        symbol text, 
        qty real, 
        pricereal
    )
''')

插入数据

普通方式

组装原始sql语句进行插入，这种使用字符串拼接的方法不安全，可能会被sql注入

db_conn.execute(r'''
INSERT INTO stocks VALUES ('2001-01-11', 'BUY', 'RHAT', 100, 35.14)
''')
db_conn.commit()

参数绑定方式

数字方式，第二个参数必须是一个tuple, 冒号后面加数字做为占位符

db_conn.execute(r'''
INSERT INTO stocks VALUES (:1, :2, :3, :4, :5)
''', ('2001-01-11', 'BUY', 'RHAT', 100, 35.14) )
db_conn.commit()

问号方式，第二个参数必须是一个tuple

db_conn.execute(r'''
INSERT INTO stocks VALUES (:1, :2, :3, :4, :5)
''', ('2001-01-11', 'BUY', 'RHAT', 100, 35.14) )
db_conn.commit()

命名方式， 第二个参数能够是一个tuple或者是dict

db_conn.execute(r'''
INSERT INTO stocks VALUES (:aa, :bb, :cc, :dd, :ee)
''', ('2001-01-11', 'BUY', 'RHAT', 100, 35.14) )

db_conn.execute(r'''INSERT INTO stocks VALUES (:aa, :bb, :cc, :dd, :ee)
''', {'aa': '2001-01-11', 'bb': 'BUY', 'cc': 'RHAT', 'dd':100, 'ee': 35.14} )

db_conn.execute(r'''INSERT INTO stocks (date, trans, symbol, qty, price) VALUES (:aa, :bb, :cc, :dd, :ee)
''', {'aa': '2001-01-11', 'bb': 'BUY', 'cc': 'RHAT', 'dd':100, 'ee': 35.14} )
db_conn.commit()

这三种方式就和字符串的format的用法差很少

executemany插入多条数据

能够把问号替换成上面讲的其余占位符号

purchases = [('2006-03-28', 'BUY', 'IBM', 1000, 45.00),
             ('2006-04-05', 'BUY', 'MSFT', 1000, 72.00),
             ('2006-04-06', 'SELL', 'IBM', 500, 53.00),
            ]
db_conn.executemany(r'''
INSERT INTO stocks VALUES (?,?,?,?,?)
''', purchases)
db_conn.commit()

查询数据

fetchone 查询单条数据 fetchall 查询全部数据 fetchmany 查询指定数目的数据 它们的返回结果是tuple或者tuple数组，若是没有数据就返回None

for row in c.execute('SELECT * FROM stocks ORDER BY price'):
        print(row)

游标使用

提交与回滚操做必须仍是由db_conn来进行处理

import sqlite3

db_conn = sqlite3.connect('example.db')
db_cur = db_conn.cursor()

#使用游标建表
db_cur.execute(r'''
CREATE TABLE IF NOT EXISTS stocks (date text, trans text, symbol text, qty real, price real)
''')

#使用游标插入数据
db_cur.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','RHAT',100,35.14)")

#数据库链接进行提交操做
db_conn.commit()
db_conn.close()

其余说明

executescript一次性执行多句sql

db_conn.executescript(r'''
    create table person(
        firstname,
        lastname,
        age
    );

    create table book(
        title,
        author,
        published
    );

    insert into book(title, author, published)
    values (
        'Dirk Gently''s Holistic Detective Agency',
        'Douglas Adams',
        1987
    );
''')

结合上下文协议管理来链接的关闭with的使用

python上下文协议文档

db_conn = sqlite3.connect(":memory:")
db_conn.execute("create table person (id integer primary key, firstname varchar unique)")

# 将会在with语句结束后自动调用db_conn.commit()来进行提交
with db_conn:
    db_conn.execute("insert into person(firstname) values (?)", ("Joe",))

# 在抛异常时将会自动调用db_conn.rollback()来进行回滚，可是异常仍然会被抛出
try:
    with db_conn:
        db_conn.execute("insert into person(firstname) values (?)", ("Joe",))
except sqlite3.IntegrityError:
    print("couldn't add Joe twice")